A Study of Institutionalized Mentally Retarded Patients in Manitoba. I: Classification and Preventability

Abstract

This preliminary report concerns the types, and the possibility of prevention, of mental retardation found among 406 patients < 20 yr of age and with IQs .ltoreq. 50 who were admitted to institutions for the retarded in Manitoba, Canada prior to 1977. The retardation appeared to be of genetic origin in 27.8% of cases and acquired in a further 30.3%. Of the genetic 31% dnd 55% of the acquired, or 25.4% of the total group, are considered to have been avoidable, given the full application of current techniques and knowledge. Idiopathic or unexplained cases comprise 41.9% of the total group, though there was suggestive evidence that a significant proportion of these cases may have an acquired etiology. Some reasons for the high proportion of idiopathic cases are discussed, and suggestions are made as to how the current burden of mental retardation may be reduced.